1. Field of the Invention
The invention is directed to a writing tip for a ball point pen with a ball receiving bore for a writing ball worked into the tip housing, with a circumferential support face inclined towards a central feed bore and arranged between this feed bore and the receiving bore with supply channels discharging into the central feed bore and into the support surface and with spherically-shaped support zones matched to the ball.
2. Description of the Related Art
Such writing tips are known. The DE-OS 20 34 274 shows a receiving bore with its support face circumferentially located around a central ink feed bore which is penetrated buy several ink feed channels. A circumferential support zone is worked into the support surface in such a way that its individual components located on the segments between the feed channels are in contact beyond the feed channels and cover these feed channels partially toward the writing ball. This construction has several disadvantages. To begin with, the contact surface between the ball and the support zone is overall relatively large, which results in a consequent rolling resistance of the ball. On the other hand, because of the partial covering of the feed channels with respect to the ball, an interruption of the writing agent feed can easily occur, which results in failures, because the lubrication provided by the writing agent is no longer present.
A writing tip for a ball point pen is known from the U.S. Pat. No. 3,166,618 where the support zones are located on raised spots, provided upon a circumferential support surface and which form paste supply lines between themselves. In this case the rolling resistance of the support zones against the ball is lower.
A disadvantage of this construction however is that the intermediate surfaces located between the support zone and the support surface fall off relatively steeply from the spherical support zone and thus from the surface of the ball. Therefore, the transition between the zone of this feed bore and the feed lines having a relatively low capillarity and the support zones forming the ball receptacle acting in a high capillarity manner, is very abrupt, which has also a negative effect upon the writing behavior and the lubrication.